Keep in mind that other buildings should be upgraded as well, but not at that high a priority. Like Watchtower, Iron Mines, and Food storages. For example, I noticed that my Iron/food storage upgrade ratio is something like 100/60. Meaning, if you have Iron storages at level 10, your Food Storages should be all at 6.
Forge is also important at some point, but leave it at level 12 for the time being, you don’t need it upgraded anymore. Bombs are the last important item you need to make for quite a long time.
Also by the time you can autoplay safely Season 1 8-7, you can autoplay all Common quests and the starting level (or in some cases, starting two levels) of the Uncommon and Rare quests as well.
There is a trick for quickly filling a raid chest with underpowered teams - just hang near an outpost on a S1 province (say, outpost at the end of province 9 or 12), don’t overtake it, but rather kill 4 out of 5 weak heroes there and run away. Rinse, repeat. That way you will always get your easy hero kills to fill that Hero raid chest and also for the path of valor as well.
Edit: I could give you a full chart of upgrading buildings for a fresh account, but that would take quite some time since it would require me to start a new fresh account and keep an exact track of building upgrades. Don’t have the time for that right now. But I gave you the general idea, it should suffice.
Edit: Upgrading Houses to level 5 is absolutely sufficient until you start going for that level 20 Training camp.
Edit: Because of constant raiding (and because food will be needed for many other things), Watchtower should lag behind Farms in a 3/2 ratio (meaning for example, level 12 farms - level 8 watchtower)